Her work day started before 7 a.m., when three flu-sickened children were being treated in the emergency room. Ready for another 12-hour shift, pediatric nurse Lindsay Wheeler donned her stethoscope and noticed, with some surprise, that there was no long waiting line of coughing youngsters and parents in surgical masks.

That would change as the hours ticked by and worried families from across the region made their way to what has become a local ground zero for pediatric treatment of H1N1, a flu pandemic that particularly afflicts the young.

With a daily caseload that has surged as much as 80 percent, the emergency room at Children's National Medical Center allowed a glimpse on two recent days inside the deluge, at a time when lab-coated doctors and scrubs-clad nurses tend the flu-stricken, round-the-clock.

Beyond the ER's sliding glass doors, a onetime billing office has become a rapid screening unit for the flu. Overflow patients are treated in chairs set up in hallways. The waiting room is divided in two by a large blue curtain, separating children with flu symptoms from those without.

The sick tend to arrive in waves -- in the morning, after school, after work -- bleary-eyed mothers and fathers and grandparents with toddlers in arms, with infants in strollers, with stuffy-nosed school-age children. Little ones cry and pull off their miniature-size surgical masks. Some stare absently at a television overhead showing "Dora the Explorer." Many have been awake half the night.

The peak came Oct. 26, a Monday that brought in 429 patients, including 232 with flulike symptoms.

"These are just unheard-of numbers for our department," said Stephen Teach, associate chief of emergency medicine, eyeing the statistics at his computer. Although most children are cared for and sent home, a small number are hospitalized, usually for respiratory problems. The day before Halloween, 39 children were in hospital beds for longer stays with confirmed H1N1 -- the most in a single day.

No children have died during the fall flu surge at Children's, although one patient succumbed to H1N1 in the spring, the hospital said.

Last week, an average of more than 90 flu patients a day streamed into the Children's emergency room, and the hospital remained in pandemic mode, using three times as many surgical masks and rubber gloves as it did before H1N1 and relying on preprinted forms to write prescriptions for Tamiflu, the main drug used to treat swine flu.

For pediatric nurses such as Wheeler, 29, a former high school swimmer and runner who grew up in McLean, the H1N1 surge has meant constant motion -- taking temperatures, counting heart rates, listening for wheezing, pouring doses of Motrin, setting up IVs for children who need fluids quickly, and giving out cartoon stickers and soothing words.

Most children with flu symptoms are not tested for H1N1 because rapid tests are too unreliable, doctors say, and the treatment would not change. For many parents, this can be hard because they want certainty: Is it swine or not?

Frightened families

"That swine flu really scares me," said Tashaila Forbes, 26, whose daughter had been sick with flu and who was worried about her 18-month-old son, Donnell Ray, who had a fever, a cough and a history of asthma.

Usually, said Forbes, "he's a very spunky child, on the go." But in exam room 31, Donnell stayed in his mother's arms, subdued, clutching his favorite sippy cup and a small plastic bag of Trix cereal.

"It's such a new sort of illness, and it's scary for a lot of people," said Wheeler, who repeatedly explains how mild the flu can be, the signs of a worsening illness, and how important it is for children to get rest, fluids and ibuprofen or acetaminophen to bring fevers down.

The wait to have a child seen can be frustrating, so Teach often stands on a kiddie stool in the waiting room and asks for patience: The hospital has extra doctors and nurses on hand, he says, and all are working as hard as they can. "When we get to your children," he assures them, "we're going to take good care of them."

To handle the onslaught, staffing in the emergency room is up, with 20 to 25 percent more doctors and nurses assigned to each shift.

The pace has been intense, but not to a breaking point, said Daniel Fagbuyi, medical director for disaster preparedness and emergency management. "When you're in the heat of it all, you're just trying to do the best you can." A day later, someone will ask, "Do you know how many we saw yesterday?' "

On the busiest days, it has been 429, 395, 394, 393. The average daily caseload for 2008 was 220. Fagbuyi's reaction: "Wow. Go team!"

This may be all the more striking because some ER staff have fallen ill with the same flu symptoms they are treating. Before most on the staff were vaccinated, absences shot up to 25 percent.

Wheeler, the pediatric nurse, fended off illness, but many of her co-workers were out at some point. They include Jennifer Kingsnorth, 39, a nurse, staff development manager and mother of four, who was flu-stricken for a week in late October. "You just feel so bad, you're coughing and you're congested," she said.

Determined not to spread the flu to her children, Kingsnorth locked herself in her bedroom at home, and her husband took over. It was not an easy week for her family, she said, but no one else got sick.

In the emergency room, doctors say H1N1 has been less about severity and more about volume. Although the number of emergency room patients has spiked, Teach said, the percentage of hospital admissions from the ER has remained the same, averaging 12 percent. "There are lots of cases," he said, "but the very sick are few."

Continuing the fight

Still, doctors are on alert for patients with more severe infections and those who have underlying conditions that put them at greater risk.

One day this month, the sickest child with swine flu lay in the pediatric intensive care unit, two floors above the emergency room: a 1 1/2 -year-old boy attached to a sophisticated lung and heart machine. For seven days, the machine pumped blood from the boy's body, infused it with oxygen and delivered the blood back to his body.

Without the machine, said David Stockwell, medical director of the pediatric intensive care unit, the boy would have died. Now he is improving, although he remains in the hospital.

At some point in the past eight weeks, 30 children with H1N1 have been treated in the ICU, far fewer than what doctors had once imagined, said Stockwell, who noted a discernible drop in cases during the past week or so. "We thought, 'Wow, this is a bad disease, and ICUs are going to be overwhelmed,' " Stockwell recalled.

But that's not the way it turned out.

Instead, much of the pandemic has been managed in the emergency room, where Wheeler cared for Donnell as SpongeBob SquarePants cavorted on television in his exam room.

Wheeler asked questions, took measure of breathing problems, got him a dose of Decadron to reduce inflammation and stayed close while his mother coaxed him to take it. The boy resisted.

"I know," his mother said softly. "Just a little bit more." Soon, a respiratory therapist came in with an Albuterol treatment.

For Wheeler and her colleagues, the flu pandemic goes on, patient by patient. The day Wheeler saw Donnell, the boy was admitted to the hospital, the third member of his family to come down with flu symptoms. In the emergency room, a day that had started slowly became an evening so busy that, once again, some patients were being treated in hallway chairs .

Wheeler did not leave when her shift ended at 7 p. m. She stayed another hour to help the next shift settle in with the next wave of sick kids.